3.14×[(10÷2)2-(8÷2)2]×150,=3.14×9×150,=4239(立方厘米).答:它的体积是4239立方厘米.(2)4239立方厘米=0.004239立方米,0.004239×7.8=0.0330642(吨),0.0330642吨=33.0642千克.答:这根钢管重33.0642千克.